how to create a function in typescript that includes a parameter but doesn't have to have it code example
Example 1: typescript pass a function as an argunetn
class Foo {
save(callback: (n: number) => any) : void {
callback(42);
}
}
var foo = new Foo();
var strCallback = (result: string) : void => {
alert(result);
}
var numCallback = (result: number) : void => {
alert(result.toString());
}
foo.save(strCallback);
foo.save(numCallback);
Example 2: typescript annotate return type
function add(x: number, y: number): number {
return x + y;
}